The disclosure herein relates to an image forming apparatus and an image forming method for forming images on sheets.
An image forming apparatus which uses liquid developer is known as a device for forming an image on a sheet. This type of image forming apparatuses typically has a fixing device configured to fix images onto sheets. The fixing device generates high heat in order to melt toner contained in the liquid developer, which is transferred onto the sheet.
It is not necessary for a fixing device to generate heat if the fixing device uses liquid developer which has characteristics such that its components (carrier solution) permeate into a sheet and high-molecular compounds with dispersed pigment therein deposit on the surface of the sheet. However, the present inventors discovered disadvantageous properties which are likely to cause peel-off of an image formed on the sheet by means of such liquid developer.
The present inventors devised non-heating fixing techniques to prevent peel-off of an image from a sheet. According to studies of the present inventors, an image is less likely to come off from a sheet if the image formed with the aforementioned liquid developer is rubbed on the sheet. According to various studies of the present inventors, the longer a period during which an image is rubbed, the higher a fixation ratio of an image on a sheet. Further, if the image is rubbed in various directions, the fixation ratio of the image on the sheet becomes higher.
An image represented by several hues has to be formed by means of several types of liquid developer. The aforementioned fixing properties of the liquid developer depend on components of the liquid developer. Differences of pigment for determining hues of an image result in differences of the fixation ratio between color components in the image. Thus, even if the aforementioned rubbing technologies are applied, a sufficient fixation ratio may be not achieved.
The aforementioned problem is not limited only to the case where an image is formed with several hues. Even in the case of forming a single-color image, a problem of an insufficient fixation ratio is brought about if several types of liquid developer are used.
The present disclosure aims to provide an image forming apparatus and an image forming method, which achieve a high image fixation ratio under usage of several types of liquid developer.